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Herein, we summarize the synthetic approaches that have been developed for the synthesis of star-shaped molecules. Typically, to design such highly functionalized molecules, simple building blocks are first assembled through trimerization reactions, starting from commercially available starting materials. Then, these building blocks are synthetically manipulated to generate extended star-shaped molecules. We also discuss the syntheses of star-shaped molecules that contain 2,4,6-trisubstituted 1,3,5-triazine or 1,3,5-trisubstituted benzene rings as a central core and diverse substituted styrene, phenyl, and fluorene derivatives at their periphery, which endows these molecules with extended conjugation. A variety of metal-catalyzed reactions, such as Suzuki, Buchwald-Hartwig, Sonogashira, Heck, and Negishi cross-coupling reactions, as well as metathesis, have been employed to functionalize a range of star-shaped molecules. The methods described herein will be helpful for designing a wide range of intricate compounds that are highly valuable in the fields of supramolecular chemistry and materials science. Owing to space limitations, we will not cover all of the publications on this topic. Instead, we will focus on examples that were reported by our research group and other relevant recent literature. Apart from the trimerization sequence, this Minireview has been structured based on the key reactions that were used to prepare the star-shaped molecules and other higher analogues. Finally, some examples that do not fit into this classification are discussed.

A simple synthetic methodology to cyclophanes containing hydroxyl groups has been reported. The key steps involved here are: Grignard reaction, double Claisen rearrangement, and ring-closing metathesis. The strategy reported here is protecting group-free synthesis.

Ring-closing metathesis (RCM) is a useful protocol for assembling macrocycles. To synthesize normuscopyridine, and its analogues we used RCM as a key step in our strategy. Our approach to the synthesis of pyridine macrocycles involves two routes. The first approach starts with alkenylation of 2,6-bis[(phenylsulfonyl)methyl]pyridine and involves five steps with 10 % overall yield. The second route begins with Grignard addition to pyridine-2,6-dicarbo nitrile, followed by RCM and one-pot removal of the carbonyl group before hydrogenation of the double bond in 28 % overall yield. This approach has only three steps. Neither route involves the use of protecting groups. Various points of diversification are embedded in our strategy and eight different cyclophanes were assembled by adopting a general approach to these macrocyclics.

A new method to synthesize para-cyclophanes and longithorone C frameworks is reported involving alkylation, ceric ammonium nitrate oxidation and ring-closing metathesis as key steps.

It is found that the configuration of the double bond formed during the RCM depends on the order of the synthetic route.

We demonstrate a new synthetic strategy to cyclophanes containing thiophene and indole moieties via Grignard addition, Fischer indolization and ring-closing metathesis as key steps.

Here, we report a new and diversity-oriented approach to macrocyclic cyclophanes by a Grignard reaction, followed by Fischer indolization and ring-closing metathesis (RCM) as key steps. The configuration of the double bond formed during the RCM depends upon the order of synthetic sequence used. Fischer indolization followed by RCM delivers the cis isomer, whereas RCM followed by Fischer indolization gives the trans isomer.

We demonstrate a new synthetic strategy to cyclophanes containing thiophene and indole moieties via Grignard addition, Fischer indolization and ring-closing metathesis as key steps.

Ring-closing metathesis (RCM) is a useful protocol for assembling macrocycles. To synthesize normuscopyridine, and its analogues we used RCM as a key step in our strategy. Our approach to the synthesis of pyridine macrocycles involves two routes. The first approach starts with alkenylation of 2,6-bis[(phenylsulfonyl)methyl]pyridine and involves five steps with 10 % overall yield. The second route begins with Grignard addition to pyridine-2,6-dicarbo nitrile, followed by RCM and one-pot removal of the carbonyl group before hydrogenation of the double bond in 28 % overall yield. This approach has only three steps. Neither route involves the use of protecting groups. Various points of diversification are embedded in our strategy and eight different cyclophanes were assembled by adopting a general approach to these macrocyclics.

A short synthetic approach to the macrocyclic framework of longithorone C is described via ring-closing metathesis using the Grubbs 2nd generation catalyst.